diff --git a/frontend/src/dialogues/chat/MultiChatDialog.vue b/frontend/src/dialogues/chat/MultiChatDialog.vue
index 4668afc..08a0ff3 100644
--- a/frontend/src/dialogues/chat/MultiChatDialog.vue
+++ b/frontend/src/dialogues/chat/MultiChatDialog.vue
@@ -63,7 +63,9 @@
                     <div class="room-create-grid">
                         <label>
                             Raumname *
-                            <input v-model.trim="roomCreateForm.roomName" type="text" placeholder="z. B. Lounge" />
+                            <input v-model.trim="roomCreateForm.roomName" type="text" placeholder="z. B. Lounge"
+                                :class="{ 'invalid-input': roomCreateValidation.roomName }" />
+                            <span v-if="roomCreateValidation.roomName" class="room-create-error">{{ roomCreateValidation.roomName }}</span>
                         </label>
                         <label>
                             Sichtbarkeit
@@ -92,23 +94,33 @@
                         </label>
                         <label>
                             min_age
-                            <input v-model.number="roomCreateForm.minAge" type="number" min="0" />
+                            <input v-model.number="roomCreateForm.minAge" type="number" min="0"
+                                :class="{ 'invalid-input': roomCreateValidation.minAge }" />
+                            <span v-if="roomCreateValidation.minAge" class="room-create-error">{{ roomCreateValidation.minAge }}</span>
                         </label>
                         <label>
                             max_age
-                            <input v-model.number="roomCreateForm.maxAge" type="number" min="0" />
+                            <input v-model.number="roomCreateForm.maxAge" type="number" min="0"
+                                :class="{ 'invalid-input': roomCreateValidation.maxAge }" />
+                            <span v-if="roomCreateValidation.maxAge" class="room-create-error">{{ roomCreateValidation.maxAge }}</span>
                         </label>
                         <label>
                             Passwort
-                            <input v-model.trim="roomCreateForm.password" type="text" placeholder="ohne Leerzeichen" />
+                            <input v-model.trim="roomCreateForm.password" type="text" placeholder="ohne Leerzeichen"
+                                :class="{ 'invalid-input': roomCreateValidation.password }" />
+                            <span v-if="roomCreateValidation.password" class="room-create-error">{{ roomCreateValidation.password }}</span>
                         </label>
                         <label>
                             right_id
-                            <input v-model.number="roomCreateForm.rightId" type="number" min="1" />
+                            <input v-model.number="roomCreateForm.rightId" type="number" min="1"
+                                :class="{ 'invalid-input': roomCreateValidation.rightId }" />
+                            <span v-if="roomCreateValidation.rightId" class="room-create-error">{{ roomCreateValidation.rightId }}</span>
                         </label>
                         <label>
                             type_id
-                            <input v-model.number="roomCreateForm.typeId" type="number" min="1" />
+                            <input v-model.number="roomCreateForm.typeId" type="number" min="1"
+                                :class="{ 'invalid-input': roomCreateValidation.typeId }" />
+                            <span v-if="roomCreateValidation.typeId" class="room-create-error">{{ roomCreateValidation.typeId }}</span>
                         </label>
                         <label class="checkbox-label">
                             <input type="checkbox" v-model="roomCreateForm.friendsOnly" />
@@ -116,9 +128,10 @@
                         </label>
                     </div>
                     <div class="room-create-actions">
-                        <button type="button" class="send-btn" @click="sendCreateRoomCommand">Raum erstellen</button>
+                        <button type="button" class="send-btn" @click="sendCreateRoomCommand" :disabled="!canSendRoomCreate">Raum erstellen</button>
                         <button type="button" class="create-room-reset-btn" @click="resetRoomCreateForm">Zurücksetzen</button>
                     </div>
+                    <div v-if="roomCreateValidation.range" class="room-create-error room-create-error-block">{{ roomCreateValidation.range }}</div>
                     <div class="room-create-preview">
                         Kommando: <code>{{ buildRoomCreateCommandPreview() || '/cr <raumname>' }}</code>
                     </div>
@@ -200,6 +213,30 @@ export default {
             try {
                 return !!(this.menu && this.menu.administration);
             } catch (_) { return false; }
+        },
+        roomCreateValidation() {
+            const errors = {};
+            const name = (this.roomCreateForm.roomName || '').trim();
+            const minAge = this.parseOptionalInteger(this.roomCreateForm.minAge);
+            const maxAge = this.parseOptionalInteger(this.roomCreateForm.maxAge);
+            const rightId = this.parseOptionalInteger(this.roomCreateForm.rightId);
+            const typeId = this.parseOptionalInteger(this.roomCreateForm.typeId);
+            const password = this.roomCreateForm.password || '';
+
+            if (!name) errors.roomName = 'Raumname ist erforderlich.';
+            if (minAge !== null && minAge < 0) errors.minAge = 'min_age muss >= 0 sein.';
+            if (maxAge !== null && maxAge < 0) errors.maxAge = 'max_age muss >= 0 sein.';
+            if (minAge !== null && maxAge !== null && minAge > maxAge) {
+                errors.range = 'min_age darf nicht größer als max_age sein.';
+            }
+            if (password.includes(' ')) errors.password = 'Passwort darf keine Leerzeichen enthalten.';
+            if (rightId !== null && rightId <= 0) errors.rightId = 'right_id muss > 0 sein.';
+            if (typeId !== null && typeId <= 0) errors.typeId = 'type_id muss > 0 sein.';
+
+            return errors;
+        },
+        canSendRoomCreate() {
+            return Object.keys(this.roomCreateValidation).length === 0;
         }
     },
     mounted() {
@@ -332,6 +369,12 @@ export default {
         buildRoomCreateCommandPreview() {
             return this.buildRoomCreateCommand();
         },
+        parseOptionalInteger(value) {
+            if (value === null || value === undefined || value === '') return null;
+            const num = Number(value);
+            if (!Number.isFinite(num)) return null;
+            return Math.trunc(num);
+        },
         buildRoomCreateCommand() {
             const name = (this.roomCreateForm.roomName || '').trim();
             if (!name) return '';
@@ -341,20 +384,24 @@ export default {
                 parts.push(`public=${this.roomCreateForm.publicFlag}`);
             }
             if (this.roomCreateForm.gender) parts.push(`gender=${this.roomCreateForm.gender}`);
-            if (Number.isInteger(this.roomCreateForm.minAge) && this.roomCreateForm.minAge >= 0) {
-                parts.push(`min_age=${this.roomCreateForm.minAge}`);
+            const minAge = this.parseOptionalInteger(this.roomCreateForm.minAge);
+            if (minAge !== null && minAge >= 0) {
+                parts.push(`min_age=${minAge}`);
             }
-            if (Number.isInteger(this.roomCreateForm.maxAge) && this.roomCreateForm.maxAge >= 0) {
-                parts.push(`max_age=${this.roomCreateForm.maxAge}`);
+            const maxAge = this.parseOptionalInteger(this.roomCreateForm.maxAge);
+            if (maxAge !== null && maxAge >= 0) {
+                parts.push(`max_age=${maxAge}`);
             }
             const password = (this.roomCreateForm.password || '').trim();
             if (password) parts.push(`password=${password}`);
             if (this.roomCreateForm.friendsOnly) parts.push('friends_only=true');
-            if (Number.isInteger(this.roomCreateForm.rightId) && this.roomCreateForm.rightId > 0) {
-                parts.push(`right_id=${this.roomCreateForm.rightId}`);
+            const rightId = this.parseOptionalInteger(this.roomCreateForm.rightId);
+            if (rightId !== null && rightId > 0) {
+                parts.push(`right_id=${rightId}`);
             }
-            if (Number.isInteger(this.roomCreateForm.typeId) && this.roomCreateForm.typeId > 0) {
-                parts.push(`type_id=${this.roomCreateForm.typeId}`);
+            const typeId = this.parseOptionalInteger(this.roomCreateForm.typeId);
+            if (typeId !== null && typeId > 0) {
+                parts.push(`type_id=${typeId}`);
             }
             return parts.join(' ');
         },
@@ -371,15 +418,15 @@ export default {
                 this.messages.push({ id: Date.now(), user: 'System', text: 'Keine Verbindung zum Chat-Server.' });
                 return;
             }
+            if (!this.canSendRoomCreate) {
+                this.messages.push({ id: Date.now(), user: 'System', text: 'Bitte Eingaben im Raum-Formular korrigieren.' });
+                return;
+            }
             const command = this.buildRoomCreateCommand();
             if (!command) {
                 this.messages.push({ id: Date.now(), user: 'System', text: 'Bitte einen Raumnamen angeben.' });
                 return;
             }
-            if ((this.roomCreateForm.password || '').includes(' ')) {
-                this.messages.push({ id: Date.now(), user: 'System', text: 'Passwort darf keine Leerzeichen enthalten.' });
-                return;
-            }
             const payload = { type: 'message', message: command };
             if (this.debug) console.log('[Chat WS >>]', payload);
             this.sendWithToken(payload);
@@ -1800,6 +1847,11 @@ export default {
     padding: 0.35em 0.5em;
 }
 
+.invalid-input {
+    border-color: #c62828 !important;
+    background: #fff6f6;
+}
+
 .checkbox-label {
     flex-direction: row !important;
     align-items: center;
@@ -1826,6 +1878,15 @@ export default {
     color: #444;
 }
 
+.room-create-error {
+    color: #b00020;
+    font-size: 0.85em;
+}
+
+.room-create-error-block {
+    margin-top: 0.5em;
+}
+
 .chat-message {
     margin-bottom: 0.3em;
 }